Prompt user to clean their buck directory.
Prompt user to clean their buck directory.

Test Plan:
Buck build with garbage in my buckdir, verify I was prompted, verify if I cleaned
my dir cache hits worked, if I didn't there were no cache hits.

luiseduardohdbackup/buck,dsyang/buck,LegNeato/buck,brettwooldridge/buck,lukw00/buck,mogers/buck,mogers/buck,davido/buck,justinmuller/buck,mnuessler/buck,vine/buck,brettwooldridge/buck,OkBuilds/buck,neonichu/buck,ilya-klyuchnikov/buck,facebook/buck,sdwilsh/buck,neonichu/buck,liuyang-li/buck,Distrotech/buck,Distrotech/buck,daedric/buck,thinkernel/buck,facebook/buck,k21/buck,rowillia/buck,davido/buck,janicduplessis/buck,raviagarwal7/buck,belomx/open_tools,bocon13/buck,grumpyjames/buck,liuyang-li/buck,vschs007/buck,sdwilsh/buck,bocon13/buck,hgl888/buck,JoelMarcey/buck,zhan-xiong/buck,marcinkwiatkowski/buck,janicduplessis/buck,Learn-Android-app/buck,darkforestzero/buck,bocon13/buck,janicduplessis/buck,stuhood/buck,JoelMarcey/buck,grumpyjames/buck,lukw00/buck,shs96c/buck,Distrotech/buck,hgl888/buck,tgummerer/buck,Distrotech/buck,LegNeato/buck,mogers/buck,Dominator008/buck,davido/buck,Addepar/buck,ilya-klyuchnikov/buck,zpao/buck,zpao/buck,mnuessler/buck,zhan-xiong/buck,facebook/buck,justinmuller/buck,romanoid/buck,sdwilsh/buck,artiya4u/buck,dsyang/buck,MarkRunWu/buck,ilya-klyuchnikov/buck,LegNeato/buck,raviagarwal7/buck,liuyang-li/buck,pwz3n0/buck,dsyang/buck,vschs007/buck,facebook/buck,LegNeato/buck,JoelMarcey/buck,vine/buck,JoelMarcey/buck,luiseduardohdbackup/buck,nguyentruongtho/buck,neonichu/buck,1yvT0s/buck,rmaz/buck,vschs007/buck,rmaz/buck,MarkRunWu/buck,illicitonion/buck,shybovycha/buck,stuhood/buck,zhuxiaohao/buck,rhencke/buck,LegNeato/buck,raviagarwal7/buck,neonichu/buck,rowillia/buck,shybovycha/buck,mikekap/buck,thinkernel/buck,mikekap/buck,bocon13/buck,stuhood/buck,nguyentruongtho/buck,OkBuilds/buck,Learn-Android-app/buck,shybovycha/buck,dushmis/buck,sdwilsh/buck,mnuessler/buck,k21/buck,sdwilsh/buck,OkBuilds/buck,illicitonion/buck,Dominator008/buck,Distrotech/buck,k21/buck,OkBuilds/buck,rmaz/buck,darkforestzero/buck,zhan-xiong/buck,vine/buck,MarkRunWu/buck,brettwooldridge/buck,SeleniumHQ/buck,raviagarwal7/buck,siddhartharay007/buck,zhuxiaohao/buck,1yvT0s/buck,illicitonion/buck,mikekap/buck,thinkernel/buck,shybovycha/buck,GerritCodeReview/buck,zhuxiaohao/buck,Addepar/buck,justinmuller/buck,k21/buck,clonetwin26/buck,davido/buck,bocon13/buck,liuyang-li/buck,mogers/buck,daedric/buck,romanoid/buck,siddhartharay007/buck,zhan-xiong/buck,stuhood/buck,brettwooldridge/buck,belomx/open_tools,Learn-Android-app/buck,justinmuller/buck,dsyang/buck,zhuxiaohao/buck,robbertvanginkel/buck,ilya-klyuchnikov/buck,nguyentruongtho/buck,artiya4u/buck,raviagarwal7/buck,illicitonion/buck,darkforestzero/buck,pwz3n0/buck,brettwooldridge/buck,liuyang-li/buck,grumpyjames/buck,janicduplessis/buck,clonetwin26/buck,hgl888/buck,robbertvanginkel/buck,thinkernel/buck,saleeh93/buck-cutom,davido/buck,liuyang-li/buck,clonetwin26/buck,tgummerer/buck,marcinkwiatkowski/buck,robbertvanginkel/buck,dpursehouse/buck,OkBuilds/buck,darkforestzero/buck,siddhartharay007/buck,vine/buck,rmaz/buck,dsyang/buck,artiya4u/buck,marcinkwiatkowski/buck,Dominator008/buck,JoelMarcey/buck,dpursehouse/buck,tgummerer/buck,rmaz/buck,mikekap/buck,Addepar/buck,saleeh93/buck-cutom,justinmuller/buck,LegNeato/buck,vschs007/buck,pwz3n0/buck,stuhood/buck,hgl888/buck,romanoid/buck,SeleniumHQ/buck,marcinkwiatkowski/buck,marcinkwiatkowski/buck,SeleniumHQ/buck,rowillia/buck,Dominator008/buck,rhencke/buck,ilya-klyuchnikov/buck,Dominator008/buck,Dominator008/buck,dushmis/buck,romanoid/buck,robbertvanginkel/buck,rowillia/buck,pwz3n0/buck,shybovycha/buck,justinmuller/buck,illicitonion/buck,mogers/buck,dpursehouse/buck,1yvT0s/buck,Dominator008/buck,Dominator008/buck,dushmis/buck,robbertvanginkel/buck,liuyang-li/buck,rhencke/buck,vine/buck,Heart2009/buck,zhuxiaohao/buck,artiya4u/buck,janicduplessis/buck,Dominator008/buck,daedric/buck,GerritCodeReview/buck,stuhood/buck,davido/buck,marcinkwiatkowski/buck,MarkRunWu/buck,janicduplessis/buck,darkforestzero/buck,clonetwin26/buck,robbertvanginkel/buck,Heart2009/buck,illicitonion/buck,romanoid/buck,brettwooldridge/buck,pwz3n0/buck,neonichu/buck,rhencke/buck,dushmis/buck,hgl888/buck,daedric/buck,darkforestzero/buck,tgummerer/buck,brettwooldridge/buck,justinmuller/buck,marcinkwiatkowski/buck,marcinkwiatkowski/buck,bocon13/buck,stuhood/buck,ilya-klyuchnikov/buck,mnuessler/buck,stuhood/buck,shs96c/buck,darkforestzero/buck,illicitonion/buck,shs96c/buck,zhuxiaohao/buck,OkBuilds/buck,marcinkwiatkowski/buck,dushmis/buck,mread/buck,zpao/buck,vschs007/buck,lukw00/buck,daedric/buck,grumpyjames/buck,artiya4u/buck,shybovycha/buck,OkBuilds/buck,1yvT0s/buck,Addepar/buck,janicduplessis/buck,vine/buck,Heart2009/buck,dsyang/buck,k21/buck,dsyang/buck,vschs007/buck,OkBuilds/buck,robbertvanginkel/buck,LegNeato/buck,grumpyjames/buck,rmaz/buck,kageiit/buck,ilya-klyuchnikov/buck,tgummerer/buck,dsyang/buck,zhan-xiong/buck,davido/buck,facebook/buck,mikekap/buck,lukw00/buck,raviagarwal7/buck,grumpyjames/buck,vine/buck,hgl888/buck,mnuessler/buck,nguyentruongtho/buck,nguyentruongtho/buck,shs96c/buck,grumpyjames/buck,mogers/buck,shybovycha/buck,pwz3n0/buck,LegNeato/buck,k21/buck,jackminicloud/buck,mogers/buck,Distrotech/buck,bocon13/buck,zpao/buck,belomx/open_tools,ilya-klyuchnikov/buck,mread/buck,daedric/buck,zpao/buck,kageiit/buck,daedric/buck,mikekap/buck,illicitonion/buck,JoelMarcey/buck,kageiit/buck,clonetwin26/buck,lukw00/buck,lukw00/buck,rmaz/buck,ilya-klyuchnikov/buck,daedric/buck,dpursehouse/buck,pwz3n0/buck,rhencke/buck,Learn-Android-app/buck,ilya-klyuchnikov/buck,grumpyjames/buck,raviagarwal7/buck,vine/buck,darkforestzero/buck,zhan-xiong/buck,tgummerer/buck,neonichu/buck,SeleniumHQ/buck,rmaz/buck,mnuessler/buck,zhan-xiong/buck,darkforestzero/buck,k21/buck,k21/buck,darkforestzero/buck,clonetwin26/buck,Distrotech/buck,vschs007/buck,liuyang-li/buck,neonichu/buck,brettwooldridge/buck,rhencke/buck,jackminicloud/buck,davido/buck,kageiit/buck,brettwooldridge/buck,1yvT0s/buck,lukw00/buck,SeleniumHQ/buck,luiseduardohdbackup/buck,robbertvanginkel/buck,artiya4u/buck,clonetwin26/buck,Heart2009/buck,JoelMarcey/buck,LegNeato/buck,zhuxiaohao/buck,jackminicloud/buck,romanoid/buck,pwz3n0/buck,neonichu/buck,mogers/buck,saleeh93/buck-cutom,saleeh93/buck-cutom,vschs007/buck,mogers/buck,SeleniumHQ/buck,raviagarwal7/buck,rowillia/buck,1yvT0s/buck,OkBuilds/buck,grumpyjames/buck,dsyang/buck,rhencke/buck,artiya4u/buck,justinmuller/buck,ilya-klyuchnikov/buck,raviagarwal7/buck,Learn-Android-app/buck,GerritCodeReview/buck,rowillia/buck,mogers/buck,dsyang/buck,nguyentruongtho/buck,liuyang-li/buck,tgummerer/buck,vine/buck,davido/buck,zhan-xiong/buck,Dominator008/buck,k21/buck,shybovycha/buck,tgummerer/buck,dsyang/buck,sdwilsh/buck,justinmuller/buck,LegNeato/buck,shs96c/buck,justinmuller/buck,SeleniumHQ/buck,pwz3n0/buck,janicduplessis/buck,raviagarwal7/buck,janicduplessis/buck,vine/buck,shs96c/buck,SeleniumHQ/buck,dushmis/buck,pwz3n0/buck,shs96c/buck,mikekap/buck,janicduplessis/buck,JoelMarcey/buck,Distrotech/buck,illicitonion/buck,clonetwin26/buck,vine/buck,siddhartharay007/buck,artiya4u/buck,daedric/buck,OkBuilds/buck,daedric/buck,Addepar/buck,bocon13/buck,luiseduardohdbackup/buck,artiya4u/buck,mnuessler/buck,raviagarwal7/buck,tgummerer/buck,Addepar/buck,rowillia/buck,zhan-xiong/buck,mikekap/buck,rmaz/buck,MarkRunWu/buck,1yvT0s/buck,sdwilsh/buck,sdwilsh/buck,artiya4u/buck,shs96c/buck,davido/buck,clonetwin26/buck,rmaz/buck,siddhartharay007/buck,mread/buck,lukw00/buck,LegNeato/buck,raviagarwal7/buck,Dominator008/buck,Learn-Android-app/buck,marcinkwiatkowski/buck,darkforestzero/buck,luiseduardohdbackup/buck,rmaz/buck,brettwooldridge/buck,pwz3n0/buck,SeleniumHQ/buck,MarkRunWu/buck,robbertvanginkel/buck,rhencke/buck,luiseduardohdbackup/buck,Dominator008/buck,GerritCodeReview/buck,Addepar/buck,zhan-xiong/buck,rhencke/buck,robbertvanginkel/buck,bocon13/buck,zhuxiaohao/buck,sdwilsh/buck,sdwilsh/buck,sdwilsh/buck,grumpyjames/buck,dsyang/buck,dushmis/buck,lukw00/buck,mikekap/buck,lukw00/buck,vschs007/buck,marcinkwiatkowski/buck,nguyentruongtho/buck,mnuessler/buck,luiseduardohdbackup/buck,zhan-xiong/buck,rowillia/buck,rowillia/buck,tgummerer/buck,rowillia/buck,saleeh93/buck-cutom,illicitonion/buck,Addepar/buck,vschs007/buck,mikekap/buck,dushmis/buck,romanoid/buck,Heart2009/buck,brettwooldridge/buck,Distrotech/buck,shs96c/buck,luiseduardohdbackup/buck,sdwilsh/buck,stuhood/buck,zhan-xiong/buck,grumpyjames/buck,Heart2009/buck,siddhartharay007/buck,illicitonion/buck,OkBuilds/buck,1yvT0s/buck,rhencke/buck,shs96c/buck,saleeh93/buck-cutom,romanoid/buck,MarkRunWu/buck,MarkRunWu/buck,justinmuller/buck,clonetwin26/buck,bocon13/buck,luiseduardohdbackup/buck,justinmuller/buck,JoelMarcey/buck,marcinkwiatkowski/buck,zhuxiaohao/buck,rowillia/buck,robbertvanginkel/buck,artiya4u/buck,siddhartharay007/buck,shs96c/buck,OkBuilds/buck,lukw00/buck,sdwilsh/buck,Learn-Android-app/buck,daedric/buck,romanoid/buck,romanoid/buck,janicduplessis/buck,SeleniumHQ/buck,jackminicloud/buck,ilya-klyuchnikov/buck,siddhartharay007/buck,justinmuller/buck,hgl888/buck,Learn-Android-app/buck,hgl888/buck,neonichu/buck,shybovycha/buck,zpao/buck,dpursehouse/buck,dpursehouse/buck,dpursehouse/buck,robbertvanginkel/buck,k21/buck,shybovycha/buck,hgl888/buck,SeleniumHQ/buck,mread/buck,Addepar/buck,brettwooldridge/buck,vschs007/buck,SeleniumHQ/buck,JoelMarcey/buck,1yvT0s/buck,Learn-Android-app/buck,Learn-Android-app/buck,kageiit/buck,Distrotech/buck,daedric/buck,clonetwin26/buck,vschs007/buck,liuyang-li/buck,Heart2009/buck,Distrotech/buck,JoelMarcey/buck,rmaz/buck,shybovycha/buck,k21/buck,JoelMarcey/buck,JoelMarcey/buck,rowillia/buck,dushmis/buck,facebook/buck,zpao/buck,mikekap/buck,shybovycha/buck,zhan-xiong/buck,davido/buck,kageiit/buck,Addepar/buck,clonetwin26/buck,mread/buck,Addepar/buck,Heart2009/buck,shs96c/buck,Heart2009/buck,tgummerer/buck,darkforestzero/buck,illicitonion/buck,mogers/buck,dsyang/buck,raviagarwal7/buck,illicitonion/buck,kageiit/buck,grumpyjames/buck,k21/buck,davido/buck,darkforestzero/buck,mnuessler/buck,SeleniumHQ/buck,Addepar/buck,janicduplessis/buck,shs96c/buck,romanoid/buck,daedric/buck,bocon13/buck,rmaz/buck,romanoid/buck,davido/buck,rhencke/buck,facebook/buck,mread/buck,Learn-Android-app/buck,mikekap/buck,belomx/open_tools,stuhood/buck,liuyang-li/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,bocon13/buck,clonetwin26/buck,robbertvanginkel/buck,dpursehouse/buck,LegNeato/buck,marcinkwiatkowski/buck,stuhood/buck,LegNeato/buck,OkBuilds/buck,siddhartharay007/buck,k21/buck,shybovycha/buck,Addepar/buck,vschs007/buck,romanoid/buck,dushmis/buck